Gougoula Eva, Cummings Charlotte N, Xu Yugao, Lu Tao, Feng Gang, Walker Nicholas R
Chemistry-School of Natural and Environmental Sciences, Newcastle University, Bedson Building, Newcastle-upon-Tyne NE1 7RU, United Kingdom.
School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Rd. 55, 401331 Chongqing, China.
J Chem Phys. 2023 Mar 21;158(11):114307. doi: 10.1063/5.0143024.
Two isomers of a complex formed between thiazole and two water molecules, thi⋯(HO), have been identified through Fourier transform microwave spectroscopy between 7.0 and 18.5 GHz. The complex was generated by the co-expansion of a gas sample containing trace amounts of thiazole and water in an inert buffer gas. For each isomer, rotational constants, A, B, and C; centrifugal distortion constants, D, D, d, and d; and nuclear quadrupole coupling constants, χ(N) and [χ(N) - χ(N)], have been determined through fitting of a rotational Hamiltonian to the frequencies of observed transitions. The molecular geometry, energy, and components of the dipole moment of each isomer have been calculated using Density Functional Theory (DFT). The experimental results for four isotopologues of isomer I allow for accurate determinations of atomic coordinates of oxygen atoms by r and r methods. Isomer II has been assigned as the carrier of an observed spectrum on the basis of very good agreement between DFT-calculated results and a set of spectroscopic parameters (including A, B, and C rotational constants) determined by fitting to measured transition frequencies. Non-covalent interaction and natural bond orbital analyses reveal that two strong hydrogen bonding interactions are present within each of the identified isomers of thi⋯(HO). The first of these binds HO to the nitrogen of thiazole (OH⋯N), and the second binds the two water molecules (OH⋯O). A third, weaker interaction binds the HO sub-unit to the hydrogen atom that is attached to C2 (for isomer I) or C4 (for isomer II) of the thiazole ring (CH⋯O).
通过7.0至18.5 GHz的傅里叶变换微波光谱法，已鉴定出噻唑与两个水分子形成的配合物thi⋯(HO)的两种异构体。该配合物是通过在惰性缓冲气体中共同膨胀含有痕量噻唑和水的气体样品而产生的。对于每种异构体，通过将转动哈密顿量拟合到观测跃迁频率，确定了转动常数A、B和C；离心畸变常数D、D、d和d；以及核四极耦合常数χ(N)和[χ(N) - χ(N)]。使用密度泛函理论(DFT)计算了每种异构体的分子几何结构、能量和偶极矩分量。异构体I的四种同位素变体的实验结果允许通过r和r方法精确确定氧原子的原子坐标。基于DFT计算结果与通过拟合测量跃迁频率确定的一组光谱参数(包括A、B和C转动常数)之间的非常好的一致性，异构体II被指定为观测光谱的载体。非共价相互作用和自然键轨道分析表明，在鉴定出的thi⋯(HO)异构体中，每种异构体内部都存在两种强氢键相互作用。其中第一种将HO与噻唑的氮结合(OH⋯N)，第二种将两个水分子结合(OH⋯O)。第三种较弱的相互作用将HO亚基与连接到噻唑环C2(对于异构体I)或C4(对于异构体II)的氢原子结合(CH⋯O)。
